Dynamic spinal segment replacement

ABSTRACT

A vertebral body system and method having a polyaxial fastener receiving member, adjustable width plates and a pedicle screw having a pedicle threaded portion and a threaded portion for fastening to the vertebral body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/681,542, filed Nov. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/975,622, filed May 9, 2018, now U.S. Pat. No.10,507,115, which is a continuation of U.S. patent application Ser. No.14/213,856, filed on Mar. 14, 2014, now U.S. Pat. No. 9,968,460, whichclaims the benefit of U.S. Provisional Application No. 61/799,672 filedMar. 15, 2013, the contents of each of the aforementioned applicationsare hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present disclosure relates generally to the field of orthopedicmedical implants, and more particularly relates to an expandable implantand method for replacing structures such as vertebral bodies andintervertebral discs.

BACKGROUND OF THE INVENTION

The human spine serves as the main structural weight bearing support ofthe human skeleton. The spinal column comprises a plurality of vertebraeseparated by intervertebral discs. Moving down the spinal column, fivedistinct regions exist as follows: cervical, thoracic, lumbar, sacral,and coccygeal. The cervical region comprises seven vertebra; thethoracic region, twelve; the lumbar region, five; the sacral, five; andthe coccygeal, four. The cervical, thoracic, and lumbar vertebraegenerally remain separate throughout an individual's lifetime whereasthe sacral and coccygeal vertebrae fuse to form the sacrum and coccyx,respectively. In general, each vertebra consists of an anterior,cancellous, portion and a posterior arch, comprising two pedicles andtwo laminae, which support seven processes (four articular, twotransverse, and one spinous). The spinal cord runs through a passagewaybetween the anterior and posterior portions of the vertebrae.

When vertebrae and/or intervertebral discs become compromised by trauma,disease, or degeneration, the ability for the spinal column toeffectively serve it weight bearing support function is diminished.Furthermore, the spinal cord or nerve roots may subsequently becomeimpinged. As a result, an individual may experience debilitating pain,loss of spinal column stability, and/or reduced range of motion (i.e.flexion, rotation, and extension) of the spinal column. To alleviatethese issues, removal and replacement of the compromised vertebrae andintervertebral discs is often required if other non-invasive methods(i.e. drug treatment or physical therapy) prove unavailing.

One common type of vertebral injury is a burst fracture of the thoracicor lumbar portion of the spine, mainly involving the anterior and middlecolumns, and often occurring in instances of trauma or pathologicallyfrom primary or secondary neoplasms. With significant degeneration,spinal surgery becomes necessary for treating the patient. In the past,surgical goals involved spinal stabilization and/or correction ofcoronal sagittal balance. Accordingly, involved techniques were directedto stabilization of the abnormality and “fusion” techniques. Thesetechniques involve fusing or “freezing” the segment in its position,despite being an abnormal position, in order to prevent progressivelyworse conditions and to assist in pain relief. This, however, leads tochronic pain as well as progression of abnormal spinal wear and tear,resulting in degeneration of adjacent levels of fused segments. Thisresults in the return of the patient to potentially multiple surgeriesfinally resulting in Failed Back Surgery Syndrome.

Recent techniques to some degree have taken into consideration thenatural balancing of the body. In these, spinal deformity correctionsurgery is aimed at reestablishing normal physiological coronal andsagittal balance and preserving natural motion of the body. However,even these more recent procedures still fail to take in account manyaspects for providing optimal techniques consistent with the body'snatural balance and anatomy.

SUMMARY OF THE INVENTION

In one example, disclosed herein is a vertebral implant assemblyincluding:

-   -   a prosthetic vertebral body for insertion into a spinal column,        the prosthetic vertebral body having a fastener receiving        member;    -   a pedicle fastener having at least two distinct fastening        portions, the distinct fastening portions comprising a first        fastening portion receivable by the fastener receiving portion        of the prosthetic vertebral body, and a second fastening portion        configured to fasten to cancellous bone.

In one example, disclosed herein is a vertebral implant apparatusincluding:

a prosthetic vertebral body for insertion into a spinal column, thevertebral body having a vertical axis aligned in the generallongitudinal direction of the spinal column when inserted therein;

a polyaxial receiver attached to said prosthetic vertebral body, andshaped for receiving a pedicle fastener.

In one example, disclosed herein is a vertebral implant apparatusincluding:

a prosthetic vertebral body for insertion into a spinal column, thevertebral body having a vertical axis aligned in the generallongitudinal direction of the spinal column when inserted therein;

a receiver shaped for receiving a pedicle fastener, wherein the receiveris movably adjustable in a horizontal axis perpendicular to the verticalaxis of the prosthetic vertebral body to facilitate alignment withpedicles upon insertion into the spinal column.

In another exemplary aspect, processes for implanting a prostheticvertebral body are also provided. In general, the prosthetic vertebralbody may be inserted into a vertebral cavity corresponding to theremoved compromised vertebra and adjacent intervertebral discs. Theprosthetic vertebral body may then be connected to pedicles bymulti-threaded pedicle screws which are cooperatively engaged with thefastener receiving members of the prosthetic vertebral body.

Other additional devices, apparatus, structures, and processes aredescribed by reference to the drawings and detailed descriptions herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, in which:

FIG. 1 is an overhead view of a human vertebra;

FIG. 2 is a side view of a portion of a spinal column containing acompromised vertebra;

FIG. 3 is a lateral side view of a portion of a spinal column containinga compromised vertebra;

FIG. 4 is a lateral side view of one exemplary embodiment of aprosthetic vertebral body;

FIG. 5 is a posterior view of one exemplary embodiment of a prostheticvertebral body;

FIG. 6 is a posterior view of a prosthetic vertebral body of FIGS. 2 and3 according to another embodiment;

FIG. 7 is a lateral side view of one exemplary embodiment of aprosthetic vertebral body 6;

FIG. 8 is a lateral side view of one exemplary embodiment of a receivershaped for receiving a pedicle fastener according to the prostheticvertebral body of FIG. 6 ;

FIG. 9 is a posterior view of one exemplary embodiment of a receivershaped for receiving a pedicle fastener according to the prostheticvertebral body of FIG. 6 ; and

FIG. 10 is one exemplary embodiment of an unassembled pedicle screwdisclosed herein.

DETAILED DESCRIPTION

A detailed description of embodiments of the present process isdisclosed herein. However, it is to be understood that the disclosedembodiments are merely exemplary of the process and that the process maybe embodied in various and alternative forms of the disclosedembodiments. Therefore, specific procedural, structural and functionaldetails which are addressed in the embodiments disclosed herein are notto be interpreted as limiting, but merely as a basis for the claims andas a representative basis for teaching one skilled in the art tovariously employ the present disclosure.

In one or more exemplary embodiments there is disclosed herein a systemand method for implantation of prosthetic vertebral bodies andoptionally intervertebral discs (“hereinafter discs”). Disclosed hereinalso are multiple exemplary embodiments involving replacement ofvertebral bodies employing minimally invasive techniques. As describedherein, the prosthetic vertebral bodies and discs are preferablydynamically integrated to provide for the maintenance of natural anatomyand balance of forces in the vertebral column.

Shown in FIG. 1 is an exemplary generally healthy vertebra 100 astypically found in the human body. The vertebra 100 includes thevertebral body 101 set in the anterior portion of the vertebra, with theanterior being directed toward the lower portion of FIG. 1 and theposterior being directed toward the upper portion of FIG. 1 . Thevertebral body 101 is generally cylindrical, containing a hard bonyouter cortical rim and less dense cancellous bone within. Two pedicles102 extend from the vertebral body 101 toward the posterior portion tothe transverse process 103. A pair of lamina 104 extends from thetransverse process 103 to the spinous process 105 at the posterior ofthe vertebra. The vertebral foramen 106 is formed between the pedicles102 and lamina 104 wherein the spinal cord and meninges are housed.

Shown in FIG. 2 is a lateral side view of several adjacent vertebralsegments forming a vertebral column 200 in the thoracic region astypically found in the human body. The vertebral column comprises avertebral body 101 in the anterior portion of the vertebra. Pedicles 102are illustrated extending dorsally from the vertebral body 101, andshown in the posterior portion of the vertebral column are spinousprocess 105. Adjacent intervertebral discs 204 are also representedimmediately above and below the vertebral body 101.

Referring to FIG. 3 , shown therein is a lateral side view of a portionof vertebral column 200, illustrating a vertebral body segment with aburst fracture. Burst fractures are particularly severe because thefracture extends in all directions of the body. The vertebral body withthe burst fracture can be referred to as a compromised vertebral body,V_(C), and is located adjacent to upper and lower intervertebral discsD_(U) and D_(L), and between adjacent upper and lower vertebra V_(U) andV_(L). Although a burst fracture is shown in FIG. 1 , the particularreason for removal of the compromised vertebral body is not limitedherein, and can include any type of fracture, degeneration, deformity,pathology, or various other bases which may lead to instability ordefectiveness and the eventual medical decision for surgical removal.

As disclosed herein, the compromised vertebral body and any adjacentdiscs can be surgically replaced with a prosthetic vertebral body andoptionally synthetic discs. Illustrated in FIG. 4 is a lateral side viewof the portion of the vertebral column of FIG. 3 with the exception,however, that the compromised vertebral body V_(C) of FIG. 3 has beenremoved along with adjacent discs D_(U) and D_(L) and replaced with oneexemplary embodiment of a prosthetic vertebral body 1 along withadjacent artificial disc assemblies 4 and 5.

FIG. 5 is a posterior view illustrating one exemplary embodiment of aprosthetic vertebral body 1 for replacing structures such as vertebraeand intervertebral discs. The vertebral body can also be referred to asa “cage” or a “spacer.” The cage can be a single integrated unit or canbe an assembly of two or more parts. The cage can be made up of a hardbiocompatible material which can withstand the stresses normallyassociated with the vertebral column. Accordingly, the material caninclude metal, alloys or plastic, including titanium alloys, or plasticssuch as polyether ether ketone (PEEK).

The cage can also be an expandable vertebral body, thus allowingadjustment to various heights to suit the patient's proportions.Exemplary expandable cages are known in the art and include for examplethose described in U.S. Pat. Nos. 8,241,294, 8,197,546, and 7,691,147.With respect to expandability of the cage, similar mechanisms can beapplied herein or modified for dynamic replacement as described herein.

As shown in the illustrated embodiment of FIG. 5 , the prostheticvertebral body 1 is generally cylindrical and includes a sleeve member 2and an inner base member 3. The inner base member has a threaded surface10 to allow advancement into the sleeve member 2. The sleeve member 2has a threaded central aperture (not shown) on its internal surface toallow the sleeve member 2 and the inner base member 3 to operativelyengage each other. Accordingly, the longitudinal dimension of theprosthetic vertebral body 1 may be altered by varying the degree towhich the inner base member 3 is enveloped within the threaded centralaperture (not shown) of the outer cage 2.

In other embodiments, the outer threaded surface 10 can instead be aseries of ratchet notches which face the inner wall of the sleeve member2 when inserted therein. In such case, the inner surface of the sleevemember 2 has projections to engage the notches, and thus mate with thenotches of the outer surface of the inner base member 3. This allows foradjustment, and a blocking member (not shown) can be engaged with theratchet notches to lock the sleeve member 2 and inner base member 3 inplace. Such locking members are described for example in U.S. Pat. No.8,241,294.

Although the outer surface 9 of the sleeve member 2 is cylindrical ortubular in shape, in alternative embodiments the sleeve member 2 cantake the form of rectangle, square, ellipse, diamond, oval, D-shape, orany shape desired to conform and substantially match the bone structureof the compromised vertebra being replaced. The outer surface 9 can beroughened or corrugated, or can have a plurality of recesses orapertures running therethrough.

Shown in the exemplary embodiment of FIG. 5 are two polyaxial fastenerreceiving members 6 which are pivotally attached and protrude radiallyoutward from the outer cage outer surface 9 for operatively receiving afastening member. Polyaxial refers to the ability of the receivingmembers 6 to swivel, pivot or move in multiple axes, including verticaland horizontal, or in any direction, including a 360 degree swivelrotation, pivot or movement relative the vertebral body. The entirefastener receiving member 6 can be pivotal, or a portion, or a headportion thereon. This provides the doctors dynamic implantation, as thedifferent proportions of the human body can be accommodated duringsurgery.

In the exemplary embodiment shown in FIG. 5 , the replacement of thevertebral body can further comprise replacement of the adjacent discs.Accordingly, replacement further comprises insertion of an upper(superior) artificial disc assembly 4 connected to the top portion ofthe outer cage 2 and a lower (inferior) artificial disc assembly 5connected to the bottom portion of the inner member 3. The discassemblies 4 and 5 can be permanently attached to, or integrated with,the upper (superior) and lower (inferior) portions of the vertebral body1, or can be removable, or separately placed without attachment above orbelow the vertebral body 1 when implanting the device. For example, thedisc assemblies 4 and 5 can be removably joined with the use of matingsurfaces with one or more corresponding projections and/or one or morecorresponding recesses on the surface of the prosthetic vertebral body 1and disc assemblies 4 and 5. Thus, the manner in which the discassembles 4 and 5 are joined with the prosthetic vertebral body 1 arenot particularly limited.

In the exemplary embodiments, the upper artificial disc assembly 4comprises a first upper endplate 11, a second upper endplate 12, and aball and socket joint 19 between the endplates 11 and 12. The ball andsocket joint 19 provides mobility between vertebral bodies which areotherwise absent in fused procedures. Such invertebral discs are knownand commercially available in the art, such as for example ProDisc-L bySynthes®. Alternatively, the portion between the endplates 11 and 12 cancomprise a compressible portion therebetween, preferably made of abiocompatible elastomeric material. Alternatively, the intervertebraldiscs can be constructed of, or contain, a polymeric material, a springmechanism, or any other comparable compressible means known or used byone of skill in the art to promote mobility of the spine.

The lower artificial disc assembly 5 comprises a first lower endplate13, a second lower endplate 14, and a ball and socket joint 19therebetween. One or more protruding members 20 are permanently affixedon the bone side each of endplate surfaces 15 and 17 respectively. Theprotruding members 20 fit against the healthy vertebrae, V_(U) andV_(L), adjacent to the removed compromised vertebrae, V_(C), and theremoved intervertebral discs, D_(U) and D_(L), and anchor the prostheticvertebral body 1 in the correct vertical orientation.

In an alternative embodiment the first upper endplate 11 and the firstlower endplate 13 are affixed to vertebral body 1 respectively by one ormore rotating members. The rotating members will allow for horizontalrotation of the artificial disc assemblies 4 and 5 to ensure properorientation with the adjacent vertebrae V_(U) and V_(L) respectively.

In the exemplary embodiment shown in FIG. 5 , the protruding members 20are in the form of a keel. The cross-sectional profile of the keel canhave different shapes. For instance, the cross-sectional profile of thekeel can have the shape of a wedge, a truncated wedge, a triangle, atruncated triangle, a rectangle, or a square. In alternative embodimentsof the present disclosure, the protruding members 20 can be a roughsurface, and/or a surface comprising ridges, spikes, raked or straightteeth, protrusions or any combination thereof.

In alternative embodiments, the second upper endplate 12 and the secondlower endplate 14 are solid and smooth. In alternative embodiments ofthe present disclosure, the second upper endplate 12 and the secondlower endplate 14 can be roughened or corrugated, or have a plurality ofrecesses or apertures running therethrough.

FIG. 6 is a posterior view illustrating an exemplary embodiment of aprosthetic vertebral body 1 and intervertebral disc assemblies 4 and 5for replacing structures such as vertebra and intervertebral discs. FIG.7 displays a lateral view of embodiments of the prosthetic vertebralbody 1 as shown in FIG. 6 . FIGS. 8 and 9 display lateral and posteriorviews of the receiver shaped for receiving a pedicle fastener accordingto the prosthetic vertebral body 1 of FIG. 6 respectively. The polyaxialfastener receiving members 26 allow for variable angles of entry for themultithreaded screw shown in FIG. 10 . Each polyaxial fastener receivingmembers 26 cooperatively connected to a first and second adjustablewidth plate 27. Each of the two adjustable width plates 27 are securedby a plate track 28 which is permanently affixed onto the outer cageouter surface 9. The adjustable width plates have serrated bottomportions 29 (shown in FIG. 9 ) which cooperatively interact with anadjustable width screw 30 contained within by the plate track 28. Theadjustable width screw 30 has threads which are reversed for each platesuch that the distance between the two adjustable width plates 27 can bealtered by rotating the adjustable width screw 30 clockwise orcounterclockwise along the length of the adjustable width screw 30.

FIG. 10 is an unassembled multi-threaded cannulated screw comprising thefirst vertebral body fastener 7 (also referred to as “VB fastener”) andthe second cancellous fastener 8 (also referred to as “cancellousfastener”). The VB fastener 7 further comprises a central aperture 21running therethrough and a polygonal head 22. The VB fastener 7 isthreaded to operatively interact with a fastener receiving member, suchas polyaxial fastener receiving member 6 or 26 as shown in FIGS. 5 and 6respectively. The VB fastener 7 can be threaded to interact with thepolyaxial fastener receiving member which can be counterthreaded.

The cancellous fastener 8 comprises a central aperture 23 runningtherethrough and a locking means 24. The cancellous fastener 8 isthreaded to operatively interact with a pedicle of the spinal columncorresponding to the V_(c), and in particular the cancellous bone withinthe pedicle.

The polygonal head 22 and the locking means 24 are fabricated tocooperatively engage each other to from a multi-threaded pedicle screw(hereinafter “the pedicle screw”—shown as 700 in FIG. 4 ). A guide wire25 can be threaded through central apertures 21 and 23. The firstfastening portion 7 is threaded to cooperatively engage the fastenerreceiving members 6 or 26 and is adapted for metal or plastic contact.The second fastening portion 8 is preferably cancellous threaded. Thecancellous threaded portion may be in a form resembling any one of acannulated screw, a pedicle screw, or a lag screw.

Conventional pedicle screws are not developed for attaching bonedirectly to hardware (i.e. prosthetic vertebral body). Accordingly, thejoined pedicle screw described herein provides a first threaded portionfor interaction with the metal or hard plastic of the receiving memberon the prosthetic vertebral body and a second threaded portion forinteraction with the cancellous bone (i.e. cancellous fastener) of thevertebra pedicle. The threaded portion for interaction with theprosthetic body is fine threaded, or machine threaded. Thus, this finerportion can have a greater number of threads, and smaller pitch (i.e.more threads per axial distance) relative the thread of the cancellousbone fastener. Additionally, such thread can have a smaller diameterrelative the cancellous bone fastener. On the other hand, the cancellousbone is softer than the vertebral body or the metal/plastic receivingmembers and thus a machine-type thread may degenerate the cancellousbone over time. Accordingly, the portion of the screw to interact withthe cancellous bone can have a thread typical for pedicle screws knownin the art for fastening into cancellous bone. Accordingly, these willhave a have a coarser thread, akin to a wood screw, and thus a largerpitch (i.e. fewer threads per axial distance) relative the VB fastener,or the portion of the screw interacting with the prosthetic vertebralbody. Additionally, such thread can have a larger diameter relative theVB fastener.

Accordingly, the joined pedicle screw will have a finer thread towardits distal end for interaction with the vertebral body and a coarser endtoward its proximal end for interaction with the cancellous bone in thepedicles. While in the illustrated embodiment, the VB fastener andcancellous fastener are two separate pieces, in alternative embodimentsthey can be one integral unit.

Embodiments of the prosthetic vertebral body 1, in whole or in part, canbe constructed from any biocompatible material, including synthetic ornatural autograft, allograft, or xenograft tissues, and can beresorbable or non-resorbable in nature. Tissue materials can include,for example, hard tissues, connective tissues, demineralized bonematrix, and combinations thereof. Resorbable materials such as, forexample, polylactide, polyglycolide, polyorthoester, polyphosphazene,tyrosine-derived polycarbonate, bioactive glass, calcium phosphate,hydroxyapatite, and combinations thereof can be used. Non-resorbablematerials such as, for example, non-reinforced polymers,carbon-reinforced polymer composites, PEEK and PEEK composites,titanium, titanium alloys, stainless steel, cobalt chrome allows,ceramics, and combinations thereof can be used.

For some embodiments of the prosthetic vertebral body 1 it may beadvantageous, in some circumstances, to pack the outer cage outersurface 9 and areas between the second upper endplate 12 and the secondlower endplate 14 and their adjacent vertebrae, V_(U) and V_(L),respectively, with a suitable osteogenic material and/or therapeuticcomposition. Suitable osteogenic materials can include, for example,autograft, allograft, xenograft, demineralized bone, synthetic andnatural bonegraft substitutes, such as bioceramics, polymers andosteoinducive factors. These materials can be prepacked into, or onto,the prosthetic vertebral body 1 where surfaces are roughened orcorrugated, or have a plurality of recesses or apertures runningtherethrough. A separate carrier such as, for example, collagen-basedcarriers, bioceramic materials, calcium phosphate, hydroxyapatite, orany combination thereof, can be used to hold the osteogenic materials intheir desired location. The carriers can also be partially comprised oftherapeutic or infection resistant agents. The carriers can also bepartially comprised of an effective amount bone morphogenic protein,transforming growth factor β1, insulin-like growth factor 1,platelet-derived growth factor, fibroblast growth factor, LIMmineralization protein (LMP), and any combinations thereof.

In other embodiments however, no osteogenic material is employed as toavoid fusion of the adjacent vertebra and to maintain flexibility basedon the prosthetic device disclosed herein.

An exemplary embodiment for the lateral implant of the prostheticvertebral body 1 is disclosed herein involving a minimally invasivepercutaneous method. A patient can be laid on his or her side and acorpectomy performed, wherein the compromised vertebral body V_(C) andadjacent discs D_(U) and D_(L) are removed. The prosthetic vertebralbody 1 is placed in a portion of a spinal column where a compromisedvertebra, V_(C), and its adjacent intervertebral discs, D_(U) and D_(L),were located before removal of said compromised vertebra andintervertebral discs.

A jamshidi needle can be employed to burrow through one or bothremaining pedicles to the vertebral body 1. A guide wire 25 can then beattached or placed proximate to fastener receiving member 6 of theprosthetic vertebral body 1. The first vertebral body fastener 7, as ithas a central aperture 21, can be placed over the guide wire and slidthrough the pedicle to the fastener polyaxial receiving member 26 ofvertebral body 1. The first vertebral body fastener 7 can be fastened,screwed or attached to the polyaxial receiving member 26.

Next, the second cancellous fastener 8 can be screwed into the pedicle.As the second cancellous fastener 8 has wider threads than the firstvertebral body fastener 7, and also being threaded for cancellous bone,it will affix within the pedicle as it is tightened. As secondcancellous fastener 8 passes through the pedicle, its distal end closestto the vertebral body 1 will contact the first vertebral body fastener7. Fasteners 7 and 8 can then attach to one another, either throughentrance of the polygonal head of first vertebral body fastener 7 into areceiving portion in the second cancellous fastener 8. Alternatively,these can be fastened together by threading, or via reciprocal malefemale portions on either of the fasteners. The polygonal head can allowboth the vertebral body fastener 7 and second cancellous fastener 8 torotate together and be fixed within the pedicle and polyaxial receivingmember respectively. Thereafter, the guide wire can be removed. Thisprocess is repeated, either sequentially or concurrently, to fasten theprosthetic vertebral body 1 to two pedicles.

Alternatively or additionally, when inserting the vertebral body 1, theadjustable width plates 27 can be moved closer or further apart byrotating the adjustable width screw 30 clockwise or counterclockwise tooptimize the placement of the prosthetic vertebral body 1 in accordancewith the patient's anatomical interpedicular width. Additionally,vertical adjustment can be made by inserting prosthetic invertebraldiscs, disclosed herein, of varying widths.

With respect to another embodiment of the present disclosure, afterfastening the multi-threaded screws into their corresponding pedicles,the adjustable width plates 27 can be moved closer or further apart byrotating the adjustable width screw 30 clockwise or counterclockwise tooptimize the placement of the prosthetic vertebral body 1 in accordancewith the patient's anatomical interpedicular width.

After fastening the multi-threaded screw into the pedicles, if using thesecond and additionally optimizing the placement of the prostheticvertebral body 1 in accordance with the patient's anatomicalinterpedicular width, the vertical height of the prosthetic vertebralbody 1 can be expanded to fit the vertebral cavity once containing thecompromised vertebra and adjacent intervertebral discs. During expansionof the prosthetic vertebral body 1, the artificial disc assemblies 4 and5 can be acted upon to ensure proper orientation and attachment toadjacent upper and lower vertebrae, V_(U) and V_(L), respectively.Additionally, different artificial disc assemblies can be used to ensureproper orientation and attachment to adjacent upper and lower vertebraeas well as the proper orientation and attachment to the pedicles.Finally, if the incorporation of osteogenic materials and/or therapeuticcompositions is advantageous they may be incorporated to the relevantcomponents before, during, and/or after expansion of the prostheticvertebral body 1.

As will be appreciated, numerous other various and combinations of thefeatures discussed above can be employed without departing from thepresent disclosure. While embodiments of the present disclosure havebeen described in detail, the disclosure is considered to beillustrative and not restrictive in character. All changes andmodification that come within the spirit of the disclosure are to beconsidered within the scope of the disclosure.

1. A vertebral implant assembly comprising: a prosthetic vertebral bodyfor insertion into a spinal column, said prosthetic vertebral bodyhaving a fastener receiving member; and a pedicle fastener having atleast two distinct fastening portions, said distinct fastening portionscomprising a first fastening portion receivable by the fastenerreceiving member of the prosthetic vertebral body, and a secondfastening portion configured to fasten to cancellous bone, wherein thefirst fastening portion is insertable to a threaded end of said secondfastening portion.
 2. The vertebral implant assembly of claim 1 whereinthe diameter of the threads on said second fastening portion is greaterthan the diameter of any part of the first portion.
 3. The vertebralimplant assembly of claim 1 wherein the threaded portion of the firstfastening portion has a greater number of threads per axial distancethan the second fastening portion.
 4. The vertebral implant assembly ofclaim 1, wherein the second fastening portion is cancellous threaded andthe thread on the first fastening portion is configured to fasten to ametal or plastic contact.
 5. The vertebral implant assembly of claim 1,wherein the first fastening portion is attachable to the secondfastening portion to form an integrated pedicle fastener.
 6. Thevertebral implant assembly of claim 1, wherein the first fasteningportion is attachable to an end of said second fastening portion.
 7. Thevertebral implant assembly of claim 1, wherein the first fasteningportion is insertable to an end of said second fastening portion.
 8. Thevertebral implant assembly of claim 1, wherein the first fasteningportion and second fastening portion form one integral unit.
 9. Thevertebral implant assembly of claim 1, wherein the first fasteningportion and second fastening portion are distinct connectable units,which join to form the pedicle fastener.
 10. The vertebral implantassembly of claim 1, wherein the fastener receiving portion is threadedto receive the first fastening portion.
 11. The vertebral implantassembly of claim 1, wherein a portion of the first fastening portion isinsertable to an end of said second fastening portion.
 12. The vertebralimplant assembly of claim 1 further comprising a guide wire insertablethrough the central aperture.
 13. The vertebral implant assembly ofclaim 1, said assembly further comprising an artificial disc configuredto insert adjacent said prosthetic vertebral body in a spinal column.14. The vertebral implant assembly of claim 13, wherein the artificialdisc has pivoting or compressible portions to facilitate range of motionof a spinal column when the artificial disc is inserted in the spinalcolumn.
 15. The vertebral implant assembly of claim 13, wherein theartificial disc comprises a compressible elastomeric portion.
 16. Thevertebral implant assembly of claim 1, wherein the prosthetic vertebralbody is expandable in vertical direction in the longitudinal directionof the spine when inserted therein.
 17. A vertebral implant assemblycomprising: a prosthetic vertebral body for insertion into a spinalcolumn, said prosthetic vertebral body having a fastener receivingportion; and a pedicle fastener having at least two distinct fasteningportions, said distinct fastening portions comprising a first fasteningportion receivable by the fastener receiving portion of the prostheticvertebral body, and a second fastening portion configured to fasten tocancellous bone, wherein a non-cancellous bone end of the secondfastening portion is configured to be attached to a non-prostheticvertebral body end of the first receiving portion.
 18. A vertebralimplant assembly of claim 17, wherein the second fastening portion iscancellous threaded and the thread on the first fastening portion isconfigured to fasten to a metal or plastic contact.